Is there still a place for transcranial Doppler in patients with IABP?
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RESEARCH LETTER
Open Access
Is there still a place for transcranial Doppler in patients with IABP? Juliana R. Caldas1,2,3, Ronney B. Panerai4,5, Rogério Passos1 and Ludhmila A. Hajjar6,7* Transcranial Doppler (TCD), a relatively inexpensive and noninvasive tool, is often used to identify emboli, stenosis, vasospasm, brain death, and cerebral autoregulation (CA) [1]. When monitoring patients with intra-aortic balloon pump (IABP), the largest study published with TCD did not show neurological complications or deterioration of CA [2], but the occurrence of abnormal reverse cerebral blood flow velocity (CBFV) was not investigated. Diastolic flow reversal in CBFV has been described in patients with IABP [3]. This pattern implies negative CBFV in late diastole and has also been described in intracranial hypertension, brain death, and comatose patients [4]. However, the clinical significance of this dramatic alteration in the CBFV waveform pattern is still unknown. We assessed the effect of CBFV reversal on CA, in patients with IABP, as part of a randomized clinical trial [2]. After ethical approval, we included patients submitted to elective cardiac surgery, who presented reverse CBFV and provided written informed consent. CBFV (TCD) and intra-arterial blood pressure (BP) were performed over 5 min with the IABP operating a 1: 3 ratio triggered by the electrocardiogram. Second measurement was performed for 5 min without pumping assistance soon after IABP was turned OFF. CA was assessed by autoregulation index (ARI), with impaired CA defined as ARI < 4 [2].
* Correspondence: [email protected]; [email protected] 6 Department of Cardiopneumology, Universidade de São Paulo, São Paulo, Brazil 7 Surgical Intensive Care, Heart Institute, University of São Paulo, Av. Dr. Enéas de Carvalho Aguiar 44, São Paulo 05403-000, Brazil Full list of author information is available at the end of the article
Paired Student’s t test or Wilcoxon tests were used as appropriate. Six of 34 patients with IABP presented CBFV reversal, aged 63.9 ± 7.9 years, EuroSCORE 5 [range 3– 7], and echocardiogram LVEF 40% [35–45]. CBFV (p = 0.68) and BP (p = 0.08) did not show any differences between IABP-ON and IABP-OFF (Table 1). For IABP-ON, ARI was 2.0 [0.0–5.6] and 4.5 [1.6–2.6] for IABP-OFF (p = 0.028). Five patients showed impaired CA with IABP-ON; however, only 3 showed impaired CA with IABPOFF (p = 0.545). All patients increased the ARI on IABP-OFF, when compared with IABP-ON. None of the patients had a stroke or a diagnosis of brain injury, but two patients died and another two had delirium [2]. Our previous study found that IABP did not impair CA [2], but with CBFV reversal, we observed that CA was affected and the ARI increased in all patients when IABP was removed. This finding indicates that TCD can play an important role in the assessment of patients with IABP and we suggest a systematic approach for this purpose in Fig. 1. The main use of TCD in this context is to identify and manage the potential complications of CA impairment, to preven
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